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280 

proceed from the region of the "zona"; and probably have their 
origin in the cells by which the latter is surrounded. If so, the au- 
thor thinks we cannot suppose them to arise in any other way than 
that which, according to his observations, appears to be the universal 
mode of reproduction ; namely, by division of the nuclei of the pa- 
rent cells. Nor can we suppose that minuteness is any hinderance 
to their subsequent increase by the same means. 



December 17, 1840. 

The MARQUIS OF NORTHAMPTON, President, in the Chair. 

The following communications were made to the Society, viz. 

1 . " Present state of the Diamond Mines of Golconda." By T. J. 
Newbold, Esq., of the Madras Army, A.D.C. to Major- General 
Wilson, K.B. Communicated by S. H. Christie, Esq., M.A., 
Sec. R.S. 

The author gives an account of the tract of country in which the 
diamond mines of Golconda are situated, and of the processes by 
which the diamonds are obtained. The latter consist merely in 
digging out the rolled pebbles and gravel, and carrying them to small 
square reservoirs, raised on mounds, having their bottom paved with 
stones, and then carefully washing them. Dry weather is selected 
to carry on these operations, in order to avoid the inconvenience and 
expense of draining. A description is then given of the mines of 
Banaganpully, Munimudgoo, Condapilly, Sumbhulpoor, and Poonah 
in Bundlekund. 

2. " Magnetic-term Observations made at Milan." By Professor 
Carlini, Director of the Observatory at that place : also " Magnetic- 
term Observations made at Prague." By Professor Kreil, Director 
of the Observatory at that place. 

3. " On the Production of Heat by Voltaic Electricity." By J. P. 
Joule, Esq. Communicated by P. M. Roget, M.D., Sec. R.S. 

The inquiries of the author are directed to the investigation of the 
cause of the different degrees of facility with which various kinds of 
metal, of different sizes, are heated by the passage of voltaic elec- 
tricity. The apparatus he employed for this purpose consisted of a 
coil of the wire, which was to be subjected to trial, placed in a jar 
of water, of which the change of temperature was measured by a very 
sensible thermometer immersed in it : and a galvanometer, to indicate 
the quantity of electricity sent through the wire, which was estimated 
by the quantity of water decomposed by that electricity. The con- 
clusion he draws from the results of his experiments is, that the ca- 
lorific effects of equal quantities of transmitted electricity are pro- 



281 

portional to the resistances opposed to its passage, whatever may be 
the length, thickness, shape, or kind of metal which closes the cir- 
cuit : and also that, cateris paribus, these effects are in the duplicate 
ratio of the quantities of transmitted electricity ; and consequently 
also in the duplicate ratio of the velocity of transmission. He also 
infers from his researches that the heat produced by the combustion 
of zinc in oxygen is likewise the consequence of resistance to electric 
conduction. 



The President informed the Meeting that the Council had voted 
the following Address to Her Majesty, the Queen : — 

" To the Queen's Most Excellent Majesty. 

" The Humble Address of the President, Council, and Fellows 
of the Royal Society of London for improving Natural 
Knowledge. 

" Most Gracious Sovereign, 

" We, Your Majesty's most dutiful and loyal subjects, the Presi- 
dent, Council, and Fellows of the Royal Society of London for im- 
proving Natural Knowledge, approach Your Majesty with the most 
heartfelt satisfaction at the birth of the Princess Royal. We feel 
the deepest gratitude to the Almighty Disposer of events for His 
gracious protection vouchsafed to Your Majesty in your late con- 
finement, and we ardently pray that the same protection may continue 
to be long afforded to a life so precious to all the inhabitants of 
these realms. 

" It is also our most ardent hope that Your Majesty's daughter may 
grow up to be a pattern of every virtue that can adorn and dignify 
her high station, and that Your Majesty may continue to be blest 
with every happiness, both public and private." 

The President also stated to the Meeting, that the Council had 
adopted the following Address to His Royal Highness Prince Albert, 
of Saxe Coburg and Gotha : — 

" To His Royal Highness Prince Albert of Saxe-Coburg and Gotha, 
K.G., F.R.S. 

" The humble Address of the President, Council, and Fellows 
of the Royal Society of London for improving Natural 
Knowledge. 

" May it please Your Royal Highness, 

" We, the President, Council, and Fellows of the Royal Society of 
London for improving Natural Knowledge, beg leave to tender to 
Your Royal Highness our warmest congratulations on the safety and 
recovery of Your Royal Highness's Consort, our beloved Sovereign, 
and on the birth of Your Royal Highness's daughter. That she 

n 2 



282 

may be the bond of your connubial happiness is our most sincere 
wish, and also that Divine Providence may long, very long, preserve 
Your Royal Highness's life, in possession of every blessing, both as 
a husband and as a father." 

The Society then adjourned over the Christmas recess, to meet 
again on the 7th of January next. 



January 7, 1841. 
Sir JOHN W. LUBBOCK, Bart, V.P. and Treas., in the Chair. 

Julius Jeffreys, Esq., was balloted for and duly elected into the 
Society. 

The following communication was read, viz. — 

" Variation of the Magnetic Declination, Horizontal Intensity, 
and Inclination observed at Milan on the 23rd and 24th December 
1840." Communicated by Professor Carlini, Director of the Milan 
Observatory. 

A paper was also read, entitled, " On the Chorda dorsalis." By 
Martin Barry, M.D., F.R.S.S. L.& E. 

The author of this communication, after pointing out the similarity 
in appearance between an object noticed by him in the mammiferous 
ovum, and the incipient chorda dorsalis described by preceding ob- 
servers in the ova of other Vertebrata, mentions some essential dif- 
ferences between his own observations and those of others as to the 
nature and mode of origin of these objects, and their relation to sur- 
rounding parts. Von Baer, the discoverer of the chorda dorsalis, 
describes this structure as " the axis around which the first parts of 
the foetus form." Reichert supposes it to be that embryonic struc- 
ture which serves as " a support and stay " for parts developed in 
two halves. The author's observations induce him to believe that, 
instead of being " the axis around which the first parts of the foetus 
form," the incipient chorda is the last-formed row of cells, which 
have pushed previously-formed cells farther out, and that, instead of 
being merely " a support and stay " for parts developed in two 
halves, the incipient chorda occupies the centre out of which the 
"two halves" originally proceeded as a single structure, and is it- 
self in the course of being enlarged by the continued origin of fresh 
substance in its most internal part. 

The author enters into a minute comparison of the objects in ques- 
tion ; from which it appears that the incipient chorda is not, as Baer 
supposed, developed into a globular form at the fore end, but that 
the linear part is a process from the globular ; and that the pellucid 
cavity contained within the latter — a part of prime importance, being 
the main centre for the origin of new substance — is not mentioned